Convert Delisle to Wedgwood easily.

If you’ve ever stumbled across an 18th-century European science manuscript or pottery kiln manual, you might’ve seen temperatures listed in Delisle or Wedgwood units. These two scales, now obsolete, tell a story of how humans tried to make sense of heat before modern standardization. Converting between them isn’t just about numbers, it’s a peek into the challenges of early industrialization. Let’s unravel this historical puzzle.

Unit definitions

What is a Delisle (°De)?

• Description: The Delisle scale, invented by French astronomer Joseph-Nicolas Delisle in 1732, flips the script: it decreases as temperatures rise. Water boils at 0°De and freezes at 150°De.
• Symbol: °De
• Common uses: Popular in Russia for nearly a century, especially in meteorological studies.
• Definition: 1°De equals -2/3°C. The scale was calibrated using mercury thermometers.

What is a Wedgwood (°W)?

• Description: Created by English potter Josiah Wedgwood in the 1780s, this scale measured kiln temperatures by observing clay shrinkage. 0°W corresponds to 1,070°F (577°C), with each degree roughly 130°F higher.
• Symbol: °W
• Common uses: Ceramics production, particularly for determining when glazes would vitrify.
• Definition: 1°W equals approximately 120°C. The scale was based on empirical observations rather than precise physics.

Conversion formula

Converting Delisle to Wedgwood requires two steps:

1. Delisle to Celsius: °C = 100 - (°De × 2/3)
2. Celsius to Wedgwood: °W = (°C + 150) / 120

Combined formula:
°W = (100 - (°De × 2/3) + 150) / 120
Simplified:
°W = (250 - (2/3 × °De)) / 120

Example calculations

Example 1: Convert 50°De to Wedgwood

1. Celsius: 100 - (50 × 2/3) = 100 - 33.33 = 66.67°C
2. Wedgwood: (66.67 + 150) / 120 ≈ 216.67 / 120 ≈ 1.81°W

Example 2: Convert -30°De to Wedgwood

1. Celsius: 100 - (-30 × 2/3) = 100 - (-20) = 120°C
2. Wedgwood: (120 + 150) / 120 = 270 / 120 = 2.25°W

Conversion tables

Delisle to Wedgwood

Wedgwood to Delisle

Historical background

The Delisle scale emerged during the Age of Enlightenment, when scientists sought to create universal measurement systems. Joseph-Nicolas Delisle’s work in St. Petersburg led to his scale being adopted by the Russian Academy of Sciences. Ironically, it became more popular there than in his native France.

Wedgwood’s scale, on the other hand, was born from industrial necessity. Josiah Wedgwood needed a reliable way to gauge kiln heat without modern pyrometers. His method involved placing small clay cylinders in the kiln and measuring how much they shrank. Each “degree” Wedgwood corresponded to a specific shrinkage percentage, which he correlated to temperature. While innovative, the system had flaws: different clay compositions reacted unpredictably, and measurements weren’t easily reproducible.

By the mid-1800s, both scales faded as Celsius and Fahrenheit became dominant. The Delisle lingered in Russia until 1920, while Wedgwood’s method was phased out with advancing pyrometer technology.

Interesting facts

1. Reverse logic: Delisle’s scale is one of the few where temperatures decrease as heat increases. This confused even contemporaries, leading to errors in early weather records.
2. Pottery precision: A single Wedgwood degree spanned about 120°C, making it too crude for modern ceramics but revolutionary in its time.
3. Mercury dependency: Delisle’s scale relied on mercury thermometers, which limited its accuracy in extreme cold (mercury freezes at -38°C).
4. Cultural legacy: Wedgwood’s name lives on through the Wedgwood company, still renowned for fine china, though they ditched his temperature scale long ago.
5. Scientific crossover: Anders Celsius, creator of the Celsius scale, initially proposed a reversed version (0 for boiling, 100 for freezing), similar to Delisle’s approach.

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